IL33 and chronic obstructive pulmonary disease: Sanofi's IL-33 antagonist, itepekimab, has been shown in one phase III clinical trial (AERIFY-1) to reduce exacerbations in COPD by 27%, but a second study (AERIFY-2) failed to show benefit which was partly explained by the company due to the lower than expected exacerbation rate during the studies (165).